AAPT2: Fix issue where exported symbols (@+id/*) were not exported

Test: make AaptTestAppOne
Change-Id: If3218c880e83c2cfaf535a099db38504471be676
diff --git a/tools/aapt2/Android.mk b/tools/aapt2/Android.mk
index e0c9d1c..c9987b8 100644
--- a/tools/aapt2/Android.mk
+++ b/tools/aapt2/Android.mk
@@ -1,7 +1,11 @@
+LOCAL_PATH := $(call my-dir)
+
 include $(CLEAR_VARS)
 
+# Target for running host unit tests on post/pre-submit.
 .PHONY: aapt2_run_host_unit_tests
 aapt2_run_host_unit_tests: PRIVATE_GTEST_OPTIONS := --gtest_output=xml:$(DIST_DIR)/gtest/aapt2_host_unit_tests_result.xml
 aapt2_run_host_unit_tests: $(HOST_OUT_NATIVE_TESTS)/aapt2_tests/aapt2_tests
 	-$(HOST_OUT_NATIVE_TESTS)/aapt2_tests/aapt2_tests $(PRIVATE_GTEST_OPTIONS) > /dev/null 2>&1
 
+include $(call all-makefiles-under,$(LOCAL_PATH))